Developing device, process unit and image forming apparatus

摘要

Provided is a developing device for developing an electrostatic latent image on an image carrier, the developing device comprising: a housing having an opening; a developing sleeve facing the image carrier through the opening; a magnet roller encased in the developing sleeve and having magnetic poles including (i) a first magnetic pole having a strongest magnetic force of all the magnetic poles and (ii) a second magnetic pole having a magnetic force equal to or larger than a predetermined value and being different from the first magnetic pole; and a positioning member operable to allow the magnet roller to rotate together with the developing sleeve when the magnet roller is in a first rotational position where the first or the second magnetic pole faces an edge of the opening located downstream in a transfer direction of a two-component developer, and to inhibit the rotation of the magnet roller when the magnet roller is in a second rotational position where the first magnetic pole is closest to the image carrier.